Dying yellow chromate on acid zinc plating

Has anyone come up with a way to dye yellow chromate on chloride zinc? We currently use an olive drab but would like to achieve the same color which can be produced from a yellow on cyanide or alkaline zinc baths. Any techniques?

Frank Zemo-Paterson, New Jersey

(1998)

Frank,
I have used yellow on chloride zinc with decent results as long as the brightener content was not too high on an old bath. Buy a yellow from a reputable company, one that specializes in zinc would be my choice. Yellow on zinc requires a less active chromate than cadmium, and cadmium will cause problems (poisons the process). Talk to the lab of the company before you buy and get their words of wisdom. I would talk to two before I made a decision. I would even send sample parts to see what it looks like. There are only three companies that I would personally buy from. We are not allowed to state which ones at this site.
Good luck, Jim

James Watts- Navarre, Florida

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